Molecular basis:
Zhang et al. (2014) reported the same molecular basis of colour-sidedness in yaks as in cattle, namely (as reported by Durkin et al., 2012) "colour sidedness is determined by a first allele on chromosome 29 (Cs(29)), which results from the translocation of a 492-kilobase chromosome 6 segment encompassing KIT to chromosome 29, and a second allele on chromosome 6 (Cs(6)), derived from the first by repatriation of fused 575-kilobase chromosome 6 and 29 sequences to the KIT locus" [see OMIA 001576-9913]

Medugorac et al. (2017) provided evidence that the colour-sided variant in yaks is due to introgression into yaks from Mongolian Turano cattle that have been herded with Mongolian yaks for more than 1,500 years, enabling the backcrossing of female yak-cattle hybrids to male yaks.